Legumes are a botanical family of plants that include dozens of varieties of beans, lentils, garbanzos, peas, soybeans, and peanuts. While eating plants would generally be thought of as healthy, the part of the legume that we eat is actually the seed of the legume plant. As with grains, the seeds of legumes store a large amount of energy in the form of carbohydrate, which may or may not support healthy metabolic function. Legumes are grown agriculturally, primarily for their food grain seed, for livestock forage and silage, and as soil-enhancing green manure. Legumes are notable in that most of them have symbiotic nitrogen-fixing bacteria in structures called root nodules. Well-known legumes include alfalfa, clover, peas, beans, lentils, lupins, mesquite, carob, soybeans, peanuts, tamarind, and the woody climbing vine wisteria. Many legumes (alfalfa, clover, peas, beans, lentils, soybeans, peanuts and others) contain symbiotic bacteria called Rhizobia within root nodules of their root systems. These bacteria have the special ability of fixing nitrogen from atmospheric, molecular nitrogen (N2) into ammonia (NH3). When a legume plant dies in the field, for example following the harvest, all of its remaining nitrogen, incorporated into amino acids inside the remaining plant parts, is released back into the soil. In the soil, the amino acids are converted to nitrate (NO3-), making the nitrogen available to other plants, thereby serving as fertilizer for future crops. There are two types of legumes: mature and immature. Mature legumes are the dried seeds found inside pods that hang from the stems of certain plants. They are excellent sources of fibre (approximately 15 g/cup), rich in protein, and low in fat. Green beans and peas, commonly referred to as vegetables, are actually immature legumes because they are harvested before maturing on the plant. Legumes contain relatively low quantities of the essential amino acid methionine, as compared to whole eggs, dairy products, or meat. This means that a smaller proportion of the plant proteins, compared to proteins from eggs or meat, may be used for the synthesis of protein in humans. legumes are among the best protein sources in the plant kingdom. The low concentrations of the amino acid methionine in legumes may be compensated for simply by eating more of them. Since legumes are relatively cheap compared to meat, eating more legumes may be an alternative to meat for some. Legumes such as beans, peas, and lentils are naturally low in fat, and high in dietary fiber. They come in a wide variety of colors, shapes, and sizes, and are available as fresh, dried, canned or frozen products. While beans and lentils contain carbohydrates, they also are high in folate, phosphorus, potassium, iron, zinc, calcium, and selenium. Legumes have many of the B vitamins and are rich in antioxidants –- these can prevent cell damage. Many kinds of beans, including soybeans, are rich in saponins –- an anti-inflammatory compound which helps your immune system protect you against cancer while it lowers your cholesterol.